1. Field of the Invention
This invention relates to a blow pipe and tuyere arrangement including a lance for injecting fuel into a blast furnace, and more particularly to a blow pipe and retractable lance including a quick disconnect coupling to enable positioning the lance in the blow pipe or tuyere for injecting fuel into the hot blast flowing into the furnace and retracting the lance without the use of tools.
2. Description of the Prior Art
It is known to employ a lance for injecting fuel into the hot blast flowing through a blow pipe and tuyere into a blast furnace to increase the temperature in the furnace and reduce the amount of coke required for the smelting process. Such lances normally are rigidly mounted in a fixed position with their outlet located to discharge the fuel in the hot blast stream, either in the blow pipe or in the tuyere, so that partial or complete combustion occurs before the injected fuel enters the furnace. U.S. Pat. No. 5,333,840 discloses one such blow pipe and lance arrangement wherein the lance comprises a pair of concentric tube members defining two separate flow paths including an inner path for a powdered coal suspension fuel and an outer path for an oxidizing gas. The two tubes are joined by a bellows-like compensator box which presumably is mounted on a flange on the outwardly projecting end of a guide tube in the wall of a blow pipe. U.S. Pat. Nos. 3,758,090 and 4,921,532 also show known lances for injecting fuel into the blow pipe of a blast furnace.
It is sometimes necessary to temporarily interrupt a blast furnace smelting operation, for example, for maintenance of the furnace or the charging system supported above the furnace. When this occurs, the hot blast through the blow pipes is interrupted, and it is conventional practice to pack the tuyere outlet with mud to prevent air from being drawn through the hot blast and tuyere system by the natural chimney effect of the furnace. To pack the tuyere, a port in the end of the blow pipe opposite the tuyere is opened and a manually manipulated elongated pusher or tamping tool is inserted to push balls of mud through the blow pipe and into position at the end of the tuyere where it is compacted against the hot charge materials in the furnace to provide a seal.
The presence of a lance projecting through the side of the blow pipe to a position near the center of the pipe presents a serious obstruction to packing the tuyeres. The obstruction not only requires the operator to remain for an undesirably long time in the hostile environment, but also frequently results in an incomplete or improperly sealed tuyere. Nevertheless, since the prior art lances such as those disclosed in the above-mentioned U.S. patents could not be readily retracted, it has been the conventional practice to attempt to manipulate the mud balls past the projecting lance tip to pack the tuyeres. It is, accordingly, a primary object of the present invention to provide an improved blow pipe and lance assembly including means retractably mounting the lance in the blow pipe.
Another object is to provide such an assembly including a manually operable quick-disconnect coupling for releasably securing the lance to the guide tube of the blow pipe to permit quick, easy connection and disconnection of the lance and blow pipe.
Another object of the invention is to provide such a blow pipe and lance assembly which allows for manual connection and disconnection of a flexible fuel supply hose to the lance without the use of tools.
Another object is to provide such an assembly in which the lance is lightweight and compact such that it may be inserted and retracted, without the use of tools, by a single worker.
Another object is to provide such an assembly which is of simple design, is relatively inexpensive to manufacture and is substantially maintenance free.